Blood Spatter Analysis

Blood Spatter Used to explain events at a violent crime scene Direction blood travels Angle of impact Blood velocity (manner of death) Point of origin

Physical Properties Cohesion - blood sticks together as it falls Gravity - pulls blood downward Surface tension - blood drops that fall on a flat surface have a curved surface Edges may have spikes or extensions Satellites - small secondary droplets

6 patterns of blood spatter Passive fall (90o angle to floor)– circular drops w/secondary satellites Arterial spurts or gushes Splashes – show position of victim Smears – bleeding victim touching walls or furniture Blood Trails – victim moving from one place to another Blood Pools – victim bleeds heavily

arterial spurts splash passive fall blood pool multiple drips smear

Cast off pattern: blood from a moving object coated in blood (pipe, knife) Fine-mist spatter: high-velocity impact (gunshot) Void: empty space; victim/attacker/object moved after attack

Blood Spatter Types High velocity – gunshot wounds Medium velocity – beating, stabbing Low velocity – blunt object impact

Lines of Convergence Determine source of blood (point of origin) Draw straight lines down long axis of blood spatter

Crime-Scene Investigation of Blood Confirm the stain is blood. Visualization with Luminol Kastle-Meyer test Confirm the stain is human. ELISA test Determine blood type. Antibody test